Impact of Channel Dredging and Straightening in an Atlantic White Cedar (Chamaecyparis thyoides L. (B.S.P.)) Freshwater Tidal Wetland

Abstract

ABSTRACT Stotts, S.; Callahan, J., and Gulledge, O., 2021. Impact of channel dredging and straightening in an Atlantic white cedar (Chamaecyparis thyoides L. (B.S.P.)) freshwater tidal wetland. Journal of Coastal Research, 37(5), 973–986. Coconut Creek (Florida), ISSN 0749-0208. Once prominent up the eastern coast of the United States, freshwater wetlands with Atlantic white cedar (AWC; Chamaecyparis thyoides L. (B.S.P.)) are now vanishing due to saltwater intrusion and anthropogenic landscape alterations. This study utilizes a historic, anthropogenic disturbance to provide insight into the AWC response to salinization. A major straightening and dredging project in the 1920s, including 16 oxbow cuts, allowed brackish water to move upstream in the St. Jones River in Dover, Delaware, leading to the die-off of an AWC swamp. The sampled AWC experienced climate change, storms, hydrologic alterations, and sea-level rise. Annual ring width and suppression event chronologies were developed from dead AWC and were compared to groupings of climate variables in the predisturbance (1895–1920) and postdisturbance (1928–1958) periods. Results of the dendrochronological analysis indicate that the AWC in this study died at an average age of 49.3 years, earlier than typically expected for such species. After the straightening and dredging, the AWC experienced changes in growth response to temperature while suppression events became positively correlated with elevated temperature (p = 0.024) and high precipitation (p = 0.019). The system also showed signs of becoming more sensitive to storm events in the postdisturbance period.